Understanding cluster state update

Question

I'm reading gossip akka cluster documentation and still have one little misunderstanding about gossip.

As said in this answer , two nodes are gossiping about the value and then who seen this value. But this comes with some issue about convergence. Here's how I see this:

S - is a seen set.

The issue is at some time, only node 4 knows that convergence happened. node 1, 2 and 3 still think it does not. I'm interesting about how should node 4 deal with convergence?

Should it initiate a new gossip round that convergence happened? Or how can other nodes know about it?

Answer 1

Nodes 1-3 will still be gossiping (well, 3 probably already knows about convergence because it knows 4 has the value.) As they continue gossiping they will be exchanging notes on who has seen the value.

Node 4 (and 3 really), and all subsequent nodes knowing about convergence continue gossiping but without the random weighting mentioned in your other question. In the protocol section of your linked doc it says:

While the cluster is in a converged state the gossiper only sends a small gossip status message containing the gossip version to the chosen node. As soon as there is a change to the cluster (meaning non-convergence) then it goes back to biased gossip again.